Knife-edge bearing.



Jr HOPKINSON.

KNIFE EDGE BEARING.

APPLIOATIQH TILED JUNE 16,1911.

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Patented Dec. 26, 1911.

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.rosnrn I-IOPKINSON, or DAYTON, 0310.

KNIFE- -EDG-E BEARING.

Specification of Letters Patent. Application filed Jlune 16, 1911.Serial No. 633,577.

Patented Dec. 26 1911.

To all whom it may mean.-

Be it known that 1, Joanna HorKINsoN, a citizen of the United States,residing at Dayton, in the county of Montgomery and State of Ohio, haveinvented certain new and useful Improvements in Knife-Edge Bearings, ofwhich the following is a speci fication.

The object of my invention is. to provide.

coacting with a bearing, the knife edge be .ing usually constructed ofsteel and the coacting bearing of some other hard substance such asagate, or hardened steel.

As a result oflong experience, scale makers have found that knife edgesformed/to an angle of about degrees resting upon bearings having anotch, the sides of which diverge at about 100 degrees, give the bestresults. Of course, more or less variation from these precise angles isfound in practice, but the variation is limited by two conditions. Ifthe angle of the knife edge is made too acute it will wear away rapidly,thus interfering with the sensitiveness of the scale and also alteringthe proper relation of the different parts. If the notch in thebearingplate upon which the knife rests is formed at too wide an angle theknife edge when rotated to a considerable extent will slip from itsproper position.

In certain instances, especially in the con struction of pendulumscales, it is necessary to provide for a wider range of angular movementbetween the knife edge and. its bearing than is possible when the knifeedge is constructed with the approved degree of acutenesss. In order tosecure a.sufiicient degree of relative rotation between the knife edgeand its bearing however, it has heretofore been found necessary toreduce the angle of the knife edge down to about 30 degrees, thusintroducing an objectionable degree of wear. It will be obvious, ofcourse, that the sharper or more acute the knife edge is made the morerapidly will the use of the structure wear the knife edge toward itsbase. In the pendulum scale this rapid wear is objectionable for thereason that it increases the length of the pendulum, thereby destroyingthe-accuracy of the scale.

In the pendulum scale, however, it is necesssary to secure a degree ofangular movement of the pendulum which has heretofore rendered it.impossible to employ a knife ed c with an angle of much over 30 degrees.Tfie greater angular movement desired could not be secured by increasingthe angle of the notch in thebearing with which the knife edge coacts,for the reason that an increase of this angle beyond the limits of theusual practice would result in the knife edge slipping out of its seat.at the apex of the angle 111 its bearing when the knife edge was rotatedto an extreme position.

The object of my invention is to construct a knife edge and bearing ofsuch. form that the knife edge may have the usual approved angle ofabout 69 degrees and still have a large extent of angular-movementwithout danger of slipping from its seat in the bearin The meanswhereby-I accomplish this ob ect will more clearly appear from the.following: description and claims, taken in connection with the Iaccompanying drawlngs, 1n which- Figure 1 1s a v ew of a part of aweighing scale similar to that shown in Patent No.

- 867 ,671, granted on October 8, 1907, to O. O.

Ozias and J. Hopkinson, and illustrates a type of mechanism to which myinvention is applicable. Fig. 2 is an end view of the knife edgeelement. Fig.3 is an end view of the bearing element. Fig. 4 is a sideview of the knife edge element and bearing element in cooperativerelation to each other. Figs.'5

and 6 show the knife edge element and bearing element separated, butviewed from the same direction as in Fig. 4. Fig. 7 is a side view ofthe knife edge element and bearing element in cooperative relation, but

viewed from a position substantially at right angles to that shown inFig. 4. Fig. 8 is a view of the knife edge element alone and viewed fromthe same direction as in Fig. 7. Fig. 9 is a perspective view of thebearin Fig. 10 is a perspective view of the kni e edge element. Fig.11is a plan view of a modified form of bearing.

The type of scale illustrated in Fig. 1

necessary in this application. It is sufficient [a to. state that thearticle to be weighed is placed upon a platform connected bya lever orsystem of levers with the link'9. The

' downward pull imposed upon the link 9 by the article being weighed istransmitted to the lever 10' through the knife edge 11 and istransmitted from the lever 10 to the flexible band 12 which is woundabout and secured to the disk 13. The pendulum 16 is rigid with the disk13 and the knife edges 2 projecting from the disk 13 rest upon suitablebearings secured to the frame of the scale. It will'be apparent that theWeight of an article placed upon the scale and drawing down upon thelink 9 will cause the pendulum to rotate upon its knife edges 2 in aclockwise direction and that the amount of rotation imparted to thependulum will bear a definite relation to the weight of the articlebeing weighed. Secured to the disk 13 is an indicating hand 14 throughwhich the weight and value of the article are ascertained as describedin the patent to Ozias and Hopkinson above referred to.

Referring to the drawings, theknife edge element 50 is provided at eachend with a.

two part knife edge 5152, the edges proper of the two parts being inalinement. The sectors which form the parts 51 and 52 are disposed at anangle to each other as clearly shown in Figs. 2, 5, 8 and 10. Thebearing element 53 for the knife edge elementv 50 has two bearingsurfaces 54 and 55 disposed at an angle to each other." The anglesbetween the planes defining the knife edgesof the sectors 51 and 52 maybe substantially equal to the standard angle for knife edges Wh-lCll isapproved in scale construction. It

. will be apparent upon reference to Figs. 9

and 10 that if the knife edge element 50 is' placed upon the bearingelement 53 with the sectors 51 and 52 resting upon the surfaces 54 and55 respectively and the knife edge element 50 be then rotated inclockwise direction until the angle of the knife edge 51 with thesurface 54 is insufficient to prevent side slipping, such side slippingwill still be prevented by the engagement of-the knlfe edge 52 with thesurface 55. Under such circumstanc the surface 55 inclines upwardly at asuflicient angle to the knife edge 52 to prevent such movement.Therefore, the tendency to slde slip caused by the rotation of the knifeedge 51 upon the surface 54 will be resisted by the coaction between theknifeedge 52 55. I have thus in effect plrlovided a'flat-bearing surface54 for the ife ed e 51, thus permitting of a large extent 0 rotation andhave prevented side I 7 es such side -movement' couldnot occur by reasonof the fact that slipping by providing the knife edge 52 disthe knifeedge 52, simultaneously rotating,

occupies a position where such side slipping cannot take place withoutthe knife edge member 50and the pendulum or other .connected partriding-upward against the force of gravity on the surface 55. This, ofcourse, efiectually preventssuch side slipping.

In Fig. 11 instead of showing plane surfaces 54 and 55 I have shown veryobtuse notches defined by surfaces'55 and 54 meeting along the vertex56. The angle between the surfaces 55 and between the surfaces 54 may bealmost 180.degrees, or, as before stated, the angle may be altogetherdone away with and plane surfaces 54 and 55 used, as shown in Fig. 9. ic I preferably form the bearing surfaces 54 and 55 so that they overlapone another longitudinally of the member 53, as clearly shown in Figs.4, 6, 7 and 9. The surfaces 54 and 55 where they overlap longitudinallyof the member 53 would form a sharp angle,

but in order to prevent excessive wear upon the knife edgev member atthis point, I round the intersection of the surfaces 54 and 55, asindicated at 60 in'Fig. 9. As a further precaution against uneven wearof the knife edge member 50, I recess the overlapping parts of the knifeedge 52, as indicated at 61 in Fig. 5.

While I have referred to the knife edge elements and bearings hereindescribed as being applied to the pendulum of the scale partiallyillustrated in Fig. 1, it will be obvious'that either the knife edge andits bearing may be attached to any moving and stationary parts of ascale structure between which a wider degree of rotation is desired thanwould be permitted by the use of knife edges of standard angle employedwith bearings of the type heretofore in use. I It will also be apparentthat considerable variation may be made in the precise form of theelements herein described without de parting from the spirit of myinvention;

What Iclaim is:

1. In a device of the class. described, a pendulum, a knife edge andbearing supporting said pendulum, said lmife edge comprising two partsthe edges of which are in alinement, one with respect to the other, andsaid bearing having two parts disposed at an angle to each other,whereby said pendulum is restrained against bodily movement throughout awide range of angular movement.

I 2.111 a device of the class described, a

Pendulum, a knife edge and supprising two parts the edges of which arein oflt'set' porting said pendulum, said knife edge comalinement, onepart being angularl I with respect to the other, and said earing havingtwo plane surfaces disposed at-an f angle to each other, whereby saidpendulum is restrained against bodily movement throughout a wide rangeof angular move-- 1o ment.

, In a device of the class described, a

knife edge comprising two parts the edges of which are in alinement, onepart being oflset angularlywith respect tothe other,

"said two parts overlapping each other longitudinally and being notchedat the edge of the overlapping parts, and a bearing havfing two "fother;20

"4. In a device of the class described, a

of which are in -alinement, one part being ofi'set angularly withrespectto the other,

anda bearing having two parts disposed at an angle to. each other, thetwo parts of the bearing parts. disposed at an angle to each knife edgecomprising two parts the" edges.

joined by a curved surface,

overlapping each other and-being-- 5. ,In a device of the lassdescribed, I

knife edge comprising two'parts 51:'52, the

edges of which are in'alinement', one part being offsetangular-1y withrespect tothe" 1 other,.said two parts overlapping each otherlongitudinally and being notched at edge 61 of the overlap ing parts.

6. In a device of tlge la'ss described, a

knife edge comprising. two parts 51 and 52, the edges of which are inalinement, one

part being 'ofi'set angularly .with respect to I the other, anda-bearing havingv two parts 54-55 disposed at an angle-to each other,-said twoparts of the bearing overlapping .each other and'being joinedby. a curved .surface 60 lying below the planes of said

